如何找出谁叫方法？ [英] How to find out who called a method?

问题描述

示例：当我的方法-fooBar被调用时，我想要它登录控制台其他类调用它的其他方法。

只知道如何记录fooBar本身和它的类的方法名称：

  _cmd 
 $ b $这是可能弄清楚的吗？
  
 div class =h2_lin>解决方案

在完全优化的代码中，没有100％肯定的方式来确定某个方法的调用者。编译器可以使用尾调用优化，而编译器有效地为被调用者重新使用调用者的栈帧。

要查看一个示例，请在任何给定的方法使用gdb并查看backtrace。注意，在每个方法调用之前你都没有看到objc_msgSend（）。这是因为objc_msgSend（）对每个方法的实现进行了一次尾调用。

虽然可以编译未优化的应用程序，系统库避免了这一个问题。

这只是一个问题;实际上，你问的是如何重新创建CrashTracer或gdb？。一个非常困难的问题，在其上作出的职业。除非你想要调试工具成为你的职业生涯，否则我建议你不要走这条路。

你真的想回答什么问题？

Example: When my method -fooBar gets called, I want it to log in the console which other method of which other class called it.

Right now, I only know how to log the method name of fooBar itself and it's class, with this:

_cmd

[self class]

Is this possible to figure out?

解决方案

In fully optimized code, there is no 100% surefire way to determine the caller to a certain method. The compiler may employ a tail call optimization whereas the compiler effectively re-uses the caller's stack frame for the callee.

To see an example of this, set a breakpoint on any given method using gdb and look at the backtrace. Note that you don't see objc_msgSend() before every method call. That is because objc_msgSend() does a tail call to each method's implementation.

While you could compile your application non-optimized, you would need non-optimized versions of all of the system libraries to avoid just this one problem.

And this is just but one problem; in effect, you are asking "how do I re-invent CrashTracer or gdb?". A very hard problem upon which careers are made. Unless you want "debugging tools" to be your career, I would recommend against going down this road.

What question are you really trying to answer?

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